Abstract: In order to study the dynamic control mechanism of gas extraction negative pressure, as well as the variation of gas extraction working condition parameters under dynamic control, taking goaf and borehole in floor rock strata as the research objects, field tests were carried out on the relationship between the negative pressure state of gas extraction and several factors including gas extraction concentration, gas extraction volume, and gas velocity in the pipeline before and after the negative pressure control of different extraction states. The results show that when the gas extraction system shifts from mixed source gas extraction to homogeneous gas extraction, the orifice negative pressure increases from 1.20 kPa to 11.14 kPa, increasing by 8.28 times; the negative pressure of drilling field increases from 3.02 kPa to 43.00 kPa, increasing by 13.24 times. When the negative pressure increases to have sufficient capacity to draw air into gas extraction system, the negative pressure increases and the extraction concentration decreases during drilling in floor rock strata, and the gas concentration in drilling field decreases from 46% to 36%; although extraction concentration has been reduced, the average extraction mixing increases from 0.82 m³/min to 2.72 m³/min, increasing by 2.32 times; the amount of pure extraction increases from 0.31 m³/min to 0.98 m³/min, increasing by 2.16 times; the average extraction purity increases from 0.31 m³/min before the test to 0.98 m³/min, increasing by 2.16 times; the gas velocity in the pipeline increases from 1.82 m/s to 6.01m/s, increasing by 2.30 times. It can provide some theoretical basis for dynamic control of negative pressure of gas extraction and selection of reasonable extraction negative pressure.